GAZA, Aug 25 (Nidal al-Mughrabi/Reuters) - Tensions among radical Palestinian factions in the Gaza Strip burst into the open on Wednesday after Hamas, which controls the enclave, detained four members of the rival Islamic Jihad.

Ehab al-Ghsain, spokesman for the Hamas-run Interior Ministry, said Hamas's security force had been on a mission to free a Gazan believed to have been abducted by the Islamic Jihad men, and that all five were under interrogation.

He denied Islamic Jihad's assertion that Hamas men had confiscated equipment from the scene, the offices of a charity belonging to Islamic Jihad in Khan Younis, in southern Gaza.

Hamas has been trying to keep other Islamist movements in line in the Gaza Strip, which it has run since 2007. Islamic Jihad and other more radical factions including al Qaeda-inspired groups complain that Hamas security forces have repeatedly blocked them from firing rockets into Israel, and have sometimes seized weapons.

Hamas leaders deny any crackdown against other factions opposed to peace with Israel, but say that all groups reached an understanding to curb rocket attacks after Israel's devastating military offensive on Gaza in January 2009.

Residents of Khan Younis said a month of mounting tension between the two groups had led to sporadic scuffles and gunfire in the area. (Writing by Nidal al-Mughrabi; Editing by Kevin Liffey)